Not limiting their activities to the earthly realm, American and British spies have infiltrated the fantasy worlds of World of Warcraft and Second Life, conducting surveillance and scooping up data in the online games played by millions of people across the globe, according to newly disclosed classified documents.

Fearing that terrorist or criminal networks could use the games to communicate secretly, move money or plot attacks, the documents show, intelligence operatives have entered terrain populated by digital avatars that include elves, gnomes and supermodels.

The spies have created make-believe characters to snoop and to try to recruit informers, while also collecting data and contents of communications between players.

But for all their enthusiasm — so many CIA, FBI and Pentagon spies were hunting around in Second Life, the document noted, that a “deconfliction” group was needed to avoid collisions — the intelligence agencies may have inflated the threat.